Piezoelectric actuator module

ABSTRACT

Disclosed herein is a piezoelectric actuator module. The piezoelectric actuator module includes a flat plate. An elastic member is provided on each of opposite ends of the plate in a longitudinal direction thereof, and protrudes perpendicularly from the plate in such a way that a first end of the elastic member is coupled to an electronic device. A plate-shaped elastic body is provided on a first surface of the plate. A piezoelectric element is provided on a first surface of the elastic body. The plate-shaped elastic body is provided between the plate and the piezoelectric element, so that the overall spring constant of the piezoelectric actuator module is lowered and thus the vibrating force of the piezoelectric actuator module is increased.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2010-0000200, filed on Jan. 4, 2010, entitled “Piezoelectric ActuatorModule”, which is hereby incorporated by reference in its entirety intothis application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a piezoelectric actuator module.

2. Description of the Related Art

Several methods have been used to permit easier and more convenientcommunication between a user and a computer or a program. Recently, ahaptic device including the concept of reflecting a user's intuitiveexperience with an interface and diversifying feedback, in addition toincluding the concept of inputting by touching the device, has beenwidely used.

The haptic device has many advantages in that space is saved,manipulability is improved and convenience is achieved, it is easy tochange the specification thereof, valuation by consumers is high, and itis easy to be operated in conjunction with IT equipment. Owing to theseadvantages, the haptic device has been widely used in a variety offields including the fields of industry, traffic, service, medicalservice and mobile-equipment.

In the general haptic device, a transparent touch panel is placed to bein close contact with an image display device, such as an LCD whichdisplays an image. When a user presses and manipulates the touch panelwhile viewing the image through the touch panel, a vibration generatingmeans such as a vibration motor or a piezoelectric actuator applies thesensation of vibration to the touch panel, thus transmitting thesensation of vibration to the user.

However, among the vibration generating means, the vibration motor isproblematic in that it vibrates an entire portion of a mobile phone toapply touch feedback to a user, so that vibration transmitted throughthe touch panel to the user is reduced. Thus, recently, research on apiezoelectric actuator which vibrates a specific part to improve asensation of vibration transmitted to a user has been activelyconducted. However, it is difficult to commercialize a piezoelectricactuator module which is capable of reducing volume and increasingvibrating force.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide apiezoelectric actuator module, which has a structure optimal forincreasing vibrating force.

In a piezoelectric actuator module according to an embodiment of thepresent invention, a flat plate is provided. An elastic member isprovided on each of opposite ends of the plate in a longitudinaldirection thereof, and protrudes perpendicularly from the plate in sucha way that a first end of the elastic member is coupled to an electronicdevice. A plate-shaped elastic body is provided on a first surface ofthe plate. A piezoelectric element is provided on a first surface of theelastic body.

The elastic member may be a coil spring.

Further, the elastic member may be integrated with the plate.

The elastic member may protrude perpendicularly from a second surface ofthe plate.

The elastic member may protrude perpendicularly from the first surfaceof the plate.

A concave part may be formed in the first surface of the elastic body ina thickness direction thereof to correspond to the piezoelectricelement, so that the piezoelectric element is inserted into and securedto the concave part.

Further, a thickness of the concave part may be thicker than a thicknessof the piezoelectric element.

Further, the elastic member may include a disc protrudingperpendicularly from the plate and coupled to the electronic device, andan elastic support extending from the disc to the plate in a swirlingcurve.

Three elastic supports may be provided and extended from positionstrisecting the disc.

Four elastic supports may be provided and extended from positionsdividing the disc into four equal parts.

Further, the elastic body may be made of rubber, liquid damper ormagnetic fluid.

Various objects, advantages and features of the invention will becomeapparent from the following description of embodiments with reference tothe accompanying drawings.

The terms and words used in the present specification and claims shouldnot be interpreted as being limited to typical meanings or dictionarydefinitions, but should be interpreted as having meanings and conceptsrelevant to the technical scope of the present invention based on therule according to which an inventor can appropriately define the conceptof the term to describe most appropriately the best method he or sheknows for carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are exploded perspective views illustrating apiezoelectric actuator module according to a first embodiment of thepresent invention;

FIGS. 3 and 4 are side views illustrating the piezoelectric actuatormodule according to the first embodiment of the present invention;

FIGS. 5 and 6 are perspective views illustrating a piezoelectricactuator module according to a second embodiment of the presentinvention;

FIGS. 7 and 8 are side views illustrating the piezoelectric actuatormodule according to the second embodiment of the present invention;

FIGS. 9 and 10 are plan views illustrating the piezoelectric actuatormodule according to the second embodiment of the present invention;

FIG. 11 is an exploded perspective view illustrating a piezoelectricactuator module according to a third embodiment of the presentinvention;

FIG. 12 is a perspective view illustrating the piezoelectric actuatormodule according to the third embodiment of the present invention; and

FIG. 13 is a side view illustrating the piezoelectric actuator moduleaccording to the third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings. Herein,the same reference numerals are used throughout the different drawingsto designate the same components. Terms including “first surface” and“second surface” may be used to distinguish one component from anothercomponent, but the components should not be limited by the terms.Further, when it is determined that the detailed description of theknown art related to the present invention may obscure the gist of thepresent invention, the detailed description will be omitted.

Hereinafter, the preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIGS. 1 and 2 are exploded perspective views illustrating apiezoelectric actuator module according to a first embodiment of thepresent invention, and FIGS. 3 and 4 are side views illustrating thepiezoelectric actuator module according to the first embodiment of thepresent invention.

As shown in FIGS. 1 to 4, the piezoelectric actuator module 100according to this embodiment includes a flat plate 110, elastic members120, an elastic body 140 and piezoelectric elements 130. The elasticmembers 120 are provided on the opposite ends of the plate 110 in alongitudinal direction thereof, and protrude perpendicularly from theplate 110 in such a way that a first end of each elastic member 120 iscoupled to an electronic device. The elastic body 140 having the shapeof a plate is provided on a first surface of the plate 110. Thepiezoelectric elements 130 are provided on a first surface of theelastic body 140.

The plate 110 supports the piezoelectric elements 130 to prevent shockfrom acting on the piezoelectric elements 130 during the driving of thepiezoelectric actuator, in addition to increasing vibrating force of thepiezoelectric elements 130. The material of the plate 110 is not limitedto a special material. However, in order to stably support thepiezoelectric elements 130 and effectively transmit vibrating force fromthe piezoelectric elements 130 to the electronic device, the plate 110is preferably made of a material having a predetermined rigidity.

Further, vibrating force G satisfies equation, G=−(m×X×w²)/M (m=mass ofpart having displacement, X=displacement of piezoelectric element,w=driving frequency, M=whole mass). Referring to the equation, since theplate 110 is vibrated along with the piezoelectric elements 130, thevalue of m (mass of part having displacement) includes the mass of theplate 110, so that the value of m increases. Thus, even if the size ofeach piezoelectric element 130 is reduced, the vibrating force can bemaintained, so that the manufacturing cost of the expensivepiezoelectric element 130 can be reduced.

The elastic members 120 secure the plate 110 having the piezoelectricelements 130 to the electronic device, in addition to controlling theelasticity of the piezoelectric actuator module 100. According to thisembodiment, each elastic member 120 comprises a general coil spring.Further, the elastic members 120 protrude perpendicularly from the plate110. Two elastic members 120 are provided, respectively, on the oppositeends of the plate 110 in the longitudinal direction thereof. Here, inorder to prevent the piezoelectric actuator module 100 from tilting andprovide a more stable structure, the elastic members 120 are preferablyprovided on the opposite ends of the plate 110 to be symmetric withrespect to the central axis of the plate 110 which is perpendicular tothe longitudinal direction of the plate 110.

Meanwhile, the elastic members 120 may be formed on a second surface ofthe plate 110 which is opposite to the first surface of the plate 110having the piezoelectric elements 130 (see FIGS. 1 and 3). If necessary,the elastic members 120 may be formed on a surface of the plate 110having the piezoelectric elements 130 (see FIGS. 2 and 4).

The elastic body 140 has the shape of a plate and functions to lower theoverall spring constant of the piezoelectric actuator module 100, thusincreasing the vibrating force of the piezoelectric actuator module 100,and is provided on the first surface of the plate 110. Further, in placeof directly attaching the piezoelectric elements 130 to the firstsurface of the plate 110, after the elastic body 140 is attached to thefirst surface of the plate 110, the piezoelectric elements 130 may beattached to the first surface of the elastic body 140. This results inan improvement in the assemblability of the elastic body 140. Therefore,since the elastic body 140 can be precisely mounted on the central axisin the longitudinal direction of the plate 110, the tilting of thepiezoelectric actuator module 100 is prevented.

Meanwhile, the elastic body 140 may be made of rubber, a liquid damper,or magnetic fluid without being limited to a special material.

The piezoelectric elements 130 serve to generate vibrating force, andare provided on the first surface of the plate 110. Thus, when thepiezoelectric elements 130 generate vibrating force, the plate 110 isvibrated along with the piezoelectric elements 130. The vibrating forceis transmitted through the elastic members 120 coupled to the plate 110to the electronic device. Hereinafter, the piezoelectric elements 130will be described in detail. When power is applied to the piezoelectricelements 130, the piezoelectric elements 130 are extended or bent togenerate vibrating force, and comprises a piezoelectric sheet (ceramicpiezoelectric sheet) on which an electrode pattern is formed orlaminated piezoelectric sheets. By appropriately determining theelectrode pattern printed on the surface of the piezoelectric sheet, thepiezoelectric element 130 generate a first vibration mode and a secondvibration mode, for example, a stretching vibration mode generated inthe longitudinal direction of the piezoelectric element 130 and abending vibration mode generated in the thickness direction of thepiezoelectric element 130. Since various laminated structures andelectrode pattern structures for the piezoelectric sheet of thepiezoelectric elements 130 are widely known to those skilled in the art,a detailed description will be omitted herein.

FIGS. 5 and 6 are perspective views illustrating a piezoelectricactuator module according to a second embodiment of the presentinvention, FIGS. 7 and 8 are side views illustrating the piezoelectricactuator module according to the second embodiment of the presentinvention, and FIGS. 9 and 10 are plan views illustrating thepiezoelectric actuator module according to the second embodiment of thepresent invention.

As shown in FIGS. 5 to 10, the greatest difference between the first andsecond embodiments is the structure of an elastic member 120. Thus, aduplicate description of components common to both the first and secondembodiments will be omitted, and the structure of the elastic member 120will be mainly described.

When comparing the elastic member 120 of the second embodiment with theelastic member 120 of the first embodiment, the general coil spring iscoupled to the plate 110 in the first embodiment, but the elastic member120 is integrated with the plate 110 in the second embodiment. Forexample, the elastic members 120 may be integrated with the plate 110 bycutting and bending the opposite ends of the plate 110. Thus, thepiezoelectric actuator module of the second embodiment is advantageousin that a process of manufacturing additional elastic members 120 and aprocess of attaching the elastic members 120 to the plate 110 may beomitted.

Further, the structure of each elastic member 120 will be described indetail. The elastic member 120 includes a disc 123 and an elasticsupport 127. The disc 123 protrudes perpendicularly from the plate 110and is coupled to the electronic device. The elastic support 127 extendsfrom the disc 123 to the plate 110 in a swirling curve, andsubstantially provides an elastic force. Thus, when the piezoelectricelements 130 are vibrated, a gap between the disc 123 and the plate 110is changed by the elastic force of the elastic support 127, andvibrating force is transmitted to the electronic device. For example,three or four elastic supports 127 may be provided. In the case ofhaving three elastic supports 127, the elastic supports 127 are extendedfrom positions trisecting the disc 123 (see FIG. 9). Meanwhile, in thecase of having four elastic supports 127, the elastic supports 127 areextended from positions dividing the disc 123 into four equal parts (seeFIG. 10). This provides a stable structure.

Meanwhile, the elastic members 120 may be formed on a second surface ofthe plate 110 which is opposite to a first surface of the plate 110having the piezoelectric elements 130 (see FIGS. 5 and 7), and may beformed on the surface of the plate 110 having the piezoelectric elements130 (see FIGS. 6 and 8), as in the first embodiment.

FIG. 11 is an exploded perspective view illustrating a piezoelectricactuator module according to a third embodiment of the presentinvention, FIG. 12 is a perspective view illustrating the piezoelectricactuator module according to the third embodiment of the presentinvention, and FIG. 13 is a side view illustrating the piezoelectricactuator module according to the third embodiment of the presentinvention.

As shown in FIGS. 11 to 13, the greatest difference between the first tothird embodiments is a coupling structure of the piezoelectric elements130 with an elastic body 140. Thus, a duplicate description ofcomponents common to the embodiments will be omitted, and the couplingstructure of the piezoelectric elements 130 with the elastic body 140will be mainly described.

According to this embodiment, concave parts 145 are formed in a surfaceof the elastic body 140 in the thickness direction thereof so that thepiezoelectric elements 130 are inserted into and secured to the concaveparts 145. Here, the concave parts 145 are formed to have shapecorresponding to the piezoelectric elements 130. Since the piezoelectricelements 130 are inserted into and secured to the concave parts 145 ofthe elastic body 140, a contact area of the elastic body 140 and thepiezoelectric elements 130 is large, so that the strength of attachingthe piezoelectric elements 130 is improved. Further, since thepiezoelectric elements 130 are fixed to the concave parts 145, thefixing positions are not changed and a change in driving frequencycaused by a change in attaching positions of the piezoelectric elements130 is prevented.

Further, the concave parts 145 are formed to be thicker than thepiezoelectric elements 130, so that the exposure surface of the elasticbody 140 may be positioned to be higher than the exposure surface ofeach piezoelectric element 130. In this case, although the piezoelectricactuator module 100 comes into contact with a casing of the electronicdevice while vibrating, the piezoelectric elements 130 are not in directcontact with the casing of the electronic device, but the elastic body140 comes into contact with the casing of the electronic device.Therefore, damage to the piezoelectric elements 130 and noise generatedwhen the piezoelectric actuator module 100 contacts the casing of theelectronic device can be prevented.

Meanwhile, as shown in the drawings, the elastic members 120 accordingto this embodiment are formed on a second surface of the plate 110 whichis opposite to a first surface of the plate 110 having the piezoelectricelements 130. However, without being limited to such an arrangement, theelastic members 120 may be formed on the surface of the plate 110 havingthe piezoelectric elements 130, as in the above-mentioned embodiments.Further, the elastic members 120 according to the third embodiment shownin the drawings are equal to the elastic members 120 according to thesecond embodiment. However, each elastic member 120 may use a coilspring, as in the first embodiment.

As described above, the present invention provides a piezoelectricactuator module, in which a plate-shaped elastic body is providedbetween a plate and a piezoelectric element, so that the overall springconstant of the piezoelectric actuator module is lowered and thus thevibrating force of the piezoelectric actuator module is increased.

Further, the present invention provides a piezoelectric actuator module,in which a piezoelectric element is inserted into and secured to anelastic body, thus preventing damage to the piezoelectric element andpreventing noise caused by contact of the piezoelectric element with anelectronic device.

Furthermore, the present invention provides a piezoelectric actuatormodule, in which an elastic member is integrated with a plate, so thatthe manufacture of an additional elastic member can be omitted, thussaving manufacturing cost, and a process of assembling the elasticmember with the plate can be omitted, thus simplifying the process ofmanufacturing the piezoelectric actuator module.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

Accordingly, such modifications, additions and substitutions should alsobe understood to fall within the scope of the present invention.

1. A piezoelectric actuator module, comprising: a flat plate; an elasticmember provided on each of opposite ends of the plate in a longitudinaldirection thereof, and protruding perpendicularly from the plate in sucha way that a first end of the elastic member is coupled to an electronicdevice; a plate-shaped elastic body provided on a first surface of theplate; and a piezoelectric element provided on a first surface of theelastic body.
 2. The piezoelectric actuator module as set forth in claim1, wherein the elastic member is a coil spring.
 3. The piezoelectricactuator module as set forth in claim 1, wherein the elastic member isintegrated with the plate.
 4. The piezoelectric actuator module as setforth in claim 1, wherein the elastic member protrudes perpendicularlyfrom a second surface of the plate.
 5. The piezoelectric actuator moduleas set forth in claim 1, wherein the elastic member protrudesperpendicularly from the first surface of the plate.
 6. Thepiezoelectric actuator module as set forth in claim 1, wherein a concavepart is formed in the first surface of the elastic body in a thicknessdirection thereof to correspond to the piezoelectric element, so thatthe piezoelectric element is inserted into and secured to the concavepart.
 7. The piezoelectric actuator module as set forth in claim 6,wherein a thickness of the concave part is thicker than a thickness ofthe piezoelectric element.
 8. The piezoelectric actuator module as setforth in claim 1, wherein the elastic member comprises: a discprotruding perpendicularly from the plate and coupled to the electronicdevice; and an elastic support extending from the disc to the plate in aswirling curve.
 9. The piezoelectric actuator module as set forth inclaim 8, wherein three elastic supports are provided and extended frompositions trisecting the disc.
 10. The piezoelectric actuator module asset forth in claim 8, wherein four elastic supports are provided andextended from positions dividing the disc into four equal parts.
 11. Thepiezoelectric actuator module as set forth in claim 1, wherein theelastic body is made of rubber, liquid damper or magnetic fluid.